The present invention relates to the construction of an ink supply unit for the supply of ink to a printhead.
The invention has been developed primarily for use with printheads in the form of printhead chips configured for use in pagewidth printers. However, it will be appreciated that the invention will not be limited to this preferred printer type or structure.
Recently, for example, in PCT Application No. PCT/AU98/00550 the present applicant has proposed a pagewidth inkjet printing device which utilizes micro-electromechanical (MEMS) processing techniques in the construction of a thermal bend actuator type device for the ejection of fluid from a nozzle chamber.
Any compact but fragile page width printhead is likely to operate on the dimensions of microns and require highly accurate registration with an external world such as with an ink supply. With a full color ink supply, multiple ink channels will have to be formed on a micron scale adjacent the printhead. This is likely to require high quality and correspondingly high cost micro-machined parts.
It is an object of the present invention to provide an ink supply unit structure for fluid distribution to a printhead that overcomes or ameliorates one or more of the disadvantages of the prior art or at least offers a useful alternative thereto.
In accordance with a first aspect of the invention there is provided an ink supply unit for supplying a printhead containing an array of ink ejection nozzles, said supply unit comprising:
a first member formed having dimensions refined to a first accuracy and having a first cavity defined therein;
a second member in the form of an ink distribution manifold having a second cavity defined therein, said second cavity being adapted for the insertion of a printhead;
said second member being configured to engage said first cavity in said first member so as to define one or more chambers for the supply of ink to ink supply passages formed in said printhead;
said second member being formed having dimensions refined to a second accuracy which is higher than said first accuracy.
Preferably, the first and second members are configured to together define a series of ink storage chambers, desirably suitable for storing different colored inks.
In the preferred form the second member defines a series of discrete ink outlets that are adapted to provide ink to ink supply passages in the printhead that are adapted to supply ink to grouped sets of ink ejection nozzles.
Preferably, the second member has overall external dimensions that are substantially smaller than those of the first member.
In accordance with a second aspect of the present invention, there is provided an ink supply unit for supplying a multiple color pagewidth ink supply printhead, comprising: a first elongated member containing a series of chambers for the storage of separate color inks and formed having dimensions refined to a first accuracy and having a first elongated cavity defined therein; a second elongated member including a series of wall elements and a second elongated cavity defined therein, the second elongated cavity being adapted for the insertion of a page width ink jet printhead, the wall elements mating with corresponding elements of the first elongated member to complete the formation of the series of chambers for the supply of ink to a series of slots formed in the back of the printhead when inserted in the second elongated cavity, wherein the second elongate member is formed having dimensions refined to a second accuracy which is higher then the first accuracy.
A screen for filtering portions of the ink supply flowing through to the printhead is preferably provided, optionally as part of the second member.
The first elongated member and/or the second elongated member can include a series of baffles for reducing the acceleration of the ink within the ink supply unit.